Roof systems are made from a variety of different materials. Historically the traditional roof system for larger buildings was formed from hot bitumen. The bitumen basically is applied to the roof deck as a molten material. A layer of roofing felt is applied over the molten bitumen. This is repeated so that there are multiple layers of bitumen and multiple layers of felt. This is commonly referred to as a built-up roof.
In the very early 1970""s, single ply roofing systems were invented. These generally included a single ply of a polymeric material which was somehow fastened to a roof system. By far the most successful single ply polymeric material was ethylene propylene diene monomer rubber or EPDM. A similar material ethylene propylene monomer rubber is also employed. These systems are sensitive to some organic solvents.
Bitumens are complex mixtures of organic compounds, some of which are of such a nature as to act as a solvent or plasticizer for polymeric materials such as EPDM. Even in cases where no physical damage is evident, these materials can migrate through materials such as plasticized PVC and cause staining on the exposed surfaces.
Due to the sensitivity of these materials, they generally are not suitable for use in combination with a bituminous adhesive. Felt-backed EPDMs have been utilized and applied with a bituminous adhesive. However, in the long run they are not successful. The fleece-backed material provides a physical bonding to the bituminous adhesive overcoming the incompatibility of the EPDM to the bituminous adhesive. However, frequently the bituminous adhesive would pool up and could actually soak through the fleece-backed material, swelling and discoloring a the EPDM. As a result, the fleece-backed material is now generally applied using a polymeric adhesive such as a foam polyurethane as disclosed in Venable U.S. Pat. No. 4,996,812. One such fleece-back EPDM is disclosed in Venable U.S. Pat. No. 5,620,554. This utilizes a polyolefin adhesive layer i.e., polyethylene to bond the fleecy material to the EPDM. Polyolefins are themselves sensitive to the same organic solvents as EPOM and therefore are unsuitable for use in contact with bituminous adhesives.
Many roofers are much more familiar with the bituminous adhesive than the polyurethane adhesive and therefore are hesitant to utilize the polyurethane adhesive. Further application of polyurethane adhesives requires an investment in equipment for efficient application. Roofers who have already invested capital for equipment to apply bituminous adhesives are reluctant to invest in the newer technology.
Accordingly it is the object of the present invention to provide a single ply EPDM roof membrane which can be adhered to a roof deck utilizing a bituminous adhesive.
The present invention is premised on the realization that an EPDM membrane which incorporates both a fleecy material with a protective barrier layer between the fleecy material and the EPDM can be adhered to a roof deck utilizing a bituminous adhesive. The barrier sheet in effect protects the EPDM sheeting from the bituminous adhesive and the fleece-back material provides the physical adhesion bonding the EPDM to the roof deck with the bituminous adhesive. The objects and advantages of the present invention will be further appreciated in light of the following detailed description and drawings in which: